(1) Field of Art
The present invention relates to an electric wire bundle clamp for fixing an electric wire bundle to a chassis, a panel board or the like.
(2) Prior Art
In a conventional electric wire clamp bundle, for example as shown in FIGS. 1(A) and 1(B), C-shaped elastic curved members 2 and 3 formed by an integral molding on mounting bases 1A and 1B respectively are each in the form of a single belt, so the curved members per se are not expansible when clamping an electric wire bundle. Therefore, as the volume of the electric wire bundle to be clamped increases, the moment the diameter of the electric wire bundle exceeds even slightly the tolerance of the clamp, it becomes difficult for retaining projections 5 and 6 to engage retaining portions 8 and 9, so clamping becomes impossible. Thus, the tolerance of the clamping diameter is very small.
In order to clamp an electric wire bundle firmly without looseness, it is desirable to clamp the bundle to the limit of the above clamp tolerance. But, in the conventional electric wire bundle clamps, as mentioned above, the clamping tolerance is so small that it is difficult to effect clamping if the size of the electric wire bundle to be clamped exceeds the maximum clamp diameter even a little. Conversely, if the former is smaller even slightly than the latter, there is formed a gap between the clamp and the electric wire bundle, thus making it impossible to clamp the bundle firmly without looseness. In an effort to solve this problem, there has been proposed such an electric wire bundle clamp as shown in FIG. 1(C), in which a plurality of retaining projections 7 are formed on a C-shaped elastic curved member 4 to make the maximum clamping diameter adjustable. But, also in this case, the C-shaped elastic curved member 4 is in a mere belt form and is not elastically expansible in its arcuate direction, so it is impossible to clamp an electric wire bundle elastically firmly and thus the above-mentioned problem has not been solved yet.
Moreover, the retaining projections 5, 6 and 7 are rigidly integral with the C-shaped elastic curved members 2, 3 and 4, respectively. For unlocking, therefore, it is necessary to first create a loosened state by holding with fingers finger-hold portions 11, 12 and 13 and like portions 51, 52 and 53 provided on the mounting base side and then pushing the finger-hold portions 11, 12 and 13 inside the C-shaped elastic curved members to disengage the retaining projections 5, 6 and 7 from the mounting base side retaining portions. Therefore, in a narrow place where electric wires, electronic devices, parts, etc. are concentrated, it is very difficult to effect unclamping and handling.
Further, in such conventional clamps as shown in FIGS. 1(A) to 1(C) in which the retaining projections 5, 6 and 7 are rigidly integral with the C-shaped curved members 2, 3 and 4, it is necessary, for unlocking, to push down an end part of each finger-hold portion to create a gap between the retaining projections 5, 6 and 7 and the fore ends 8, 9 and 10 of the finger-hole portions 51, 52 and 53 engaged therewith. Particularly where the size of the electric wire bundle to be clamped is at the maximum of the clamping tolerance, the retaining projections 5, 6 and 7 are pushed against the finger-hold portions 51, 52 and 53 during clamping, so it is impossible to effect unlocking unless the fingerhold portion is pushed down to an extremely large extent to open the gap. Besides, in case the finger-hold portions 51, 52 and 53 undergo a permanent deformation or an excessive stress deformation and an upward force is exerted on the electric wire bundle and a like force exerted also on the C-shaped elastic curved members 2, 3 and 4 during clamping, the electric wire bundle is easily disengaged from the clamp. Such a drawback can be overcome by enhancing the rigidity of the C-shaped elastic curved members or that of the finger-hold portions 51, 52 and 53. In this case, however, because of the enhanced rigidity, it is no longer easy to push in the C-shaped elastic curved members 2, 3 and 4 and bend the finger-hold portions 51, 52 and 53. Thus, in such a conventional clamp, once the rigidity is enhanced to make disengagement of the clamped electric wire bundle difficult, it becomes difficult to effect unlocking. Conversely, weakening the rigidity to make unlocking easier results in the clamped electric wire bundle being disengaged more easily. Thus, the sureness of clamping and the easiness of unlocking are incompatible with each other. Further, the open ends of the C-shaped elastic curved members must be pushed in near the fore ends of the finger-hold portions 51, 52 and 53 where there is only a narrow gap, and it is troublesome to guide such open ends exactly near the fore ends of the finger-hold portions 51, 52 and 53.